Method for underwater arc welding

ABSTRACT

According to the method of this invention water is kept away from the arc in underwater arc welding by means of a gas under a pressure greater than that of the water and, preferably, the wire feeding unit, welding gun, and electrode wire of the gas shielded, metal arc welding apparatus to be used underwater are enclosed in air-tight and water-tight containers. The containers and conduits are then internally pressurized with a shield gas to prevent the entry of water. The welding gun or at least its nozzle is inserted through a flexible sealed orifice in a small local housing chamber having a second opening. This second opening is placed against the work-piece to be welded. Shielding gas is supplied to the housing chamber at a pressure greater than the surrounding water to force water from the chamber and permit welding to take place in a region free of water.

METHOD FOR UNDERWATER ARC WELDING [75] Inventor: Ernest H. Berghof, Orlando, Fla. [73] Assignee: Anna Welding Corporation,

Orlando, Fla.

[22] Filed: Aug. 7, 1972 [21] Appl. No.: 278,425

Related US. Application Data [60] Division of Ser. No. 175,220, Aug. 26, 1971, which is a division of Ser. No. 886,245, Nov. 13, 1969, Pat. No. 3,632,950, which is a continuation-in-part of Ser. No. 701,700, Jan. 30, 1968, abandoned.

[52] US. Cl 219/137, 219/72, 219/74 [51] Int. Cl B23h 9/00 [58] Field of Search 219/72, 74, 75, 130, 137

[56] References Cited UNITED STATES PATENTS 3,521,022 7/1970 Sato 219/72 2,667,751 2/1954 Osborn 219/72 3,581,042 5/1971 Pilia 219/72 2,572,796 10/1951 Woodard 2l /l37 Feb. 26, 1974 Attorney, Agent, or FirmMortenson & Weigel [57] ABSTRACT According to the method of'this invention water is kept away from the arc in underwater arc welding by means of a gas under a pressure greater than that of the water and, preferably, the wire feeding unit, welding gun, and electrode wire of the gas shielded, metal arc welding apparatus to be used underwater are enclosed in air-tight and water-tight containers. The containers and conduits are then internally pressurized with a shield gas to prevent the entry of water. The welding gun or at least its nozzle is inserted through a flexible sealed orifice in a small local housing chamber having a second opening. This second opening is placed against the work-piece to be welded. Shielding gas is supplied to the housing chamber at a pressure greater than the surrounding water to force water from the chamber and permit welding to take place in a region free of water.

10 Claims, 12 Drawing Figures PATENTED FEB28 1974 saw 3 or 4 1&2 1.30 From/20 l METHOD FOR UNDERWATER ARC WELDING BACKGROUND OF THE INVENTION This is a division of patent application Ser. No. 175,220 filed Aug. 26, 1971, entitled Method and Apparatus For Underwater Arc Welding which application is a division of patent application Ser. No. 886,245 filed Nov. 13, 1969 entitled Method and Apparatus For Underwater Arc Welding now US. Pat. No. 3,632,950 issued Jan. 4, 1972, which is a continuationin-part of an application Ser. No. 701,700 filed Jan. 30, 1968, now abandoned.

This invention relates to gas shielding and, more particularly, to gas shielded underwater electric arc welding using a consumable electrode.

At the present time underwater welds are achieved only with relatively great difficulty. In most cases, techniques employed encompass sinking a caisson over the affected area or pipe to be welded, pumping the water from within the caisson, and lowering the men and equipment into the caisson where the welding is performed. The men and equipment then are removed, water is allowed to enter the caisson and the caisson is finally removed. This procedure is not only time consuming but is expensive.

Many efforts have been made to perform underwater welding using diving equipment. In the case of electric arc welding, coated, consumable electrodes have been developed which when consumed shield the welded area sufficiently to permit a weld of shorts. Welds, however, performed underwater using this technique, are generally unsatisfactory and not of the quality of welds obtainable above water.

It is, therefore, an object of this invention to provide for underwater welding using consumable electrodes.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT According to the preferred method of .this invention, an electric are drawn between a consumable electrode and a work-piece is accomplished in underwater surroundings by forming a protective gas shield about the welding area and the weld which acts as a means for keeping the water away from the weld. Preferably, the tip of the electrode is positioned in a portable housing having an aperture therein and the housing aperture is positioned over the weld area of the work-piece. Finally, a shield gas is supplied, under a pressure greater than the surrounding water pressure, to the housing to free theme and weld of the water. A pliable gasket is positioned between the aperture and the work-piece to enhance the seal between the aperture and the workpiece. The shielding gas is passed as a coaxial stream about the tip of the electrode to protect the electrode.

Using this method, welds having the quality of dry land welds may be formed using consumable electrodes and electric arc welding techniques.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, both as to its organization and method of operation, as well as additional objects and advan tages thereof, will be further understood from the following description when read in connection with the accompanying drawings which are not limitative and, in which:

FIG. 1 is a sectional view denoting the overall disposition of the apparatus with reference to a body of water which apparatus is constructed in accordance with this invention and facilitates underwater electric arc welding;

FIG. 2 is a cross-sectional view of the nozzle portion of a welding gun constructed in accordance with this invention;

FIG. 3 is a. cross-sectional view taken along the section lines 3-3 of the tubular conduit, illustrated in FIG. 1, which interconnects the wire feeding unit with the power supply and source of shielding gas;

FIG. 4 is a partial view enlarged of the welding gun and wire feeding unit partially cut away and partially shown by dotted lines to illustrate the details of the apparatus of this invention;

FIG. 5 is a top view of the wire feeding unit seen in FIG. 4;

FIG. 6 is a side elevation view of the underwater welding gun housing chamber constructed in accordance with the preferred embodiment of this invention;

FIG. 7 is a top plan view of the welding housing chamber illustrated in FIG. 6;

FIG. 8 is an end elevation view of the welding gun housing chamber illustrated in FIG. 6;

FIG. 9 is a cross-sectional view of the welding gun housing chamber taken through the section line 9-9 of FIG. 6;

FIG. 10 is a fragmented view of the welding gun housing chamber, with welding gun in operating position, taken along the section line l0-l0 of FIG. 7;

FIG. 11 is a sectional view of the welding gun housing chamber taken along the section line 11-11 of FIG. 7; and

FIG. 12 is a fragmentary view ofa contacting gasket, used with the welding gun housing chamber, adapted to fit a cylindrical work-piece.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT According to the method of this invention, underwater electric arc welding may be accomplished using gas shielding techniques. An electric arc is drawn between an elongated consumable electrode and the workpiece, and this are is protected from the surrounding water by forming an inner annular stream of shielding gas about the electrode and then flowing this inner stream along the axis of the arc coaxially about the arc. The shielding gas may be any of those conventionally used in gas shielded arc welding processes. Among these gases suitable for shielding are the inert gases helium, neon, argon, krypton, xenon and radon which are useful for welding of non-ferrous metals. Of these inert gases, helium and argon are the most used because of their relatively low cost. Argon is typically used with 1 to 5 percent oxygen.

To improve the penetration pattern of the weld, carbon dioxide also may be used for either ferrous or nonferrous welding. Carbon dioxide may also be used as the shielding gas either along or in combination with any of the other gases. Indeed, carbon dioxide may be used as the outer shield only, the inner shield being eliminated. In many instances, the double shield is used in order to get the desired protection against chemical reaction by using the inert gases, but in instances in which chemical reaction at the weld is a minor problem or unlikely, one will use the inexpensive carbon dioxide extensively.

Whatever the shield gas employed, the outer annular gas stream is used for it is also used to protect the equipment. The outer stream is usually ejected from the welding gun nozzle. Each of the annular streams of shielding gas is generally directed from the end portion of the electrode assembly toward the workpiece and must have sufficient pressure above that of the surrounding water, to maintain the weld area and are substantially free of water. In typical applications, welding is accomplished in water depths up to 150 feet and greater. Sufficiently high shielding gas pressures must be used to permit the flow of shielding gas into the water to protect the arc and weld area on the workpiece. In this manner, the many advantages of dry land or atmospheric electric arc welding using a shielding gas are obtained. It is also possible to lead the pressurized gas to the work-piece separately and apart from the welding gun or the wire feed. In such procedure the pressurized gas stream is generally directed across the arc and is not annular with the arc. The annular stream is preferred for convenience and ease of manipulation. Among these advantages of atmospheric arc welding are included are stabilization, stronger welds, and others.

In alternative embodiments, the outer stream of shielding gas may be composed of air, if desired, for, generally the inner sheath is generally sufficient to shield the arc itself.

The method of this invention is further described by reference to the apparatus illustrated in the drawings. In FIG. 1 for example there is illustrated a welding machine or power source and blower 10 which is resting on the floor of a boat or barge 12. The power source 10 may comprise a conventional source which provides a generator and suitable rectification and control equipment, if desired, to provide a direct current (D.C.) source of power and pressurized air. This source 10 should also have such control circuitry as is necessary to provide the necessary or desired output current characteristics.

Positioned on one end of the power supply is a source of shielding gas illustrated by the reinforced cylinder 14. Running from the power supply and blower l and shielding gas supply 14 is a tubular conduit 16 which passes downwardly through the water 1 8 to a conventional wire feeding unit with controls illustrated by the box 20. The conduit 16, as may be noted in the crosssectional view of FIG. 3, comprises a tube, and enclosed within the tube 16 area power cable 22, a ground wire 24, a shielding gas line 26 and a I10 volt A.C. supply 28 which supplies the necessary current for a the wire feed drive motor in unit 20. The shielding gas supply 14 supplies both the gas line 26 and the tube 16 with shielding gas. Alternatively, the tube 16 may be supplied with air by the blower portion of the power source 10 or by another pressurized supply similar to the reinforced cylinder 14.

A conventional wire feeding unit and control is enclosed within the box 20. As is seen more clearly in FIG. 4, the conduit 16 is placed over a nipple 32 formed in the exterior of the box 20 and clamped as by a band clamp 34 of conventional type (FIG. 5). The interior of the box 20 includes the wire drive 60 which is shown as a box by way of illustration only. This wire drive, as is well known, automatically drives the consumable elongated electrode from a supply reel 38 at may be provided on the box to facilitate carrying. Box

20 may be formed of any suitable metal or other container capable of rough handling and may haven an open upper side which is closed by a top plate which may be bolted as by bolts 52 to the edges of the sides of the box 20. A sealing gasket 54 may insure a watertight seal, if necessary.

The drive for the wire or consumable electrode 94 is illustrated as the box positioned inside container 20. Connected to pass through box 60 are the several power and ground cables along the shielding gas conduit 26, these elements issuing from the conduit 16 which is connected to the inlet to box 20. Thus, the electrode wire issuing from box 60 is surrounded by the inner shielding gas as it passes to gun 64.

From the wire drive unit 60, the consumable electrode 94 passes through a guide tube 62 which contains the shielding gas from the shielding gas supply tube 26 and is connected directly to the welding gun 64 which is illustrated in dotted lines. The welding gun 64 includes a trigger switch 66 which closes a circuit in the control box 60 to actuate the wire feed. The are is established when the electrode is in proper relationship to the work-piece 70. A ground line 68 is connected from the exterior of the control box 20 to the workpiece 70 illustrated as an underwater pipe 70. The guide tube 62, as well as the welding gun 64, are enclosed within a tubular conduit 74 which is similar to the conduit 16. The conduit 74 also is placed over a nipple 96 in one side of the box 20 and clamped as by a clamp 34'to maintain a water-tight connection. This permits outer shielding gas which flows through the interior of the input conduit 16 to pass into the interior of box 20, through the box 20 and through the outgoing conduit 74 to completely pressurize the entire system and, as will be described, to provide an outer shield of gas about the arc. The conduits 16 and 74 may be formed of any suitablerubber or rubberized or plastic fabric which is waterproof and impermeable and is reasonably flexible so as to permit the trigger 66 to be actuated by hand. In the alternative, the trigger switch 66 may be placed on the exterior of the conduit 74.

The welding gun 64 includes a conventional nozzle 76 (dotted lines) to which the conduit 74 is connected and is sealed as by a clamp 34. The details of the nozzle construction are seen, in the enlarged view of FIG. 2, which shows the consumable electrode 94 passing through the guide tube 62 and entering the tapered tubular section of nozzle 76. The flow of shielding gas from the guide tube 62 forms an inner sheath 80 about the are 82 formed between the consumable electrode 92 and the work-piece 70. This means that the actual weld 84 is surrounded by the shielding gas and chemical destruction of the metal is avoided.

If desired, to further insure the shielding of the weld 84 and are 82, the nozzle 76 is surrounded by a coaxially disposed tube section 86. This tube section is retained by the clamp 34 in sealed coaxial relationship with the tube 74 (FIG. 4). It is coaxially positioned about the nozzle 76 as by means of thumbscrews 88. The section 86 may be formed of any suitable rigid ma- The shield gas used for this outer sheath may be any of those previously described, but in addition may, for example, simply be air pumped in from the atmosphere as by the blower 10, if the expense of using shield gas for this purpose is considered too great. A chemically inactive gas is, however, preferred. The outer sheath shield gas may be a conventional shield gas and may be the same as or different than the inner sheath of shield gas.

Using the apparatus of this invention, a diver will submerge to the work area carrying along with him the wire feed and control box 20 and the welding gun. Someone onthe surface will start the power supply and blower unit and open the shield gas supply 14. The welder adjusts the wire feed speed, connects the ground wire and, when ready, squeezes upon the trigger switch 66. This establishes the electric arc between the consumable electrode and the work-piece. The are thus formed is protected by the double sheath of shielding gas which is permitted to escape as it forces water away so that welding takes place within a pocket of shielding gas thus providing the many advantages of welding upon dry land.

The box 20, if desired, may include a pressure actuated switch which will de-energize the power unit 10 in the event of a loss of pressure. A loss of pressure usually would mean that a rip in one of the tubes or a failure of the shielding gas supply occurred. The pressure actuated switch provides a safety disconnection in the event it is deemed desirable. Additional control features may be introduced if desired. For example, control of the welding current may also be adjustable from underwater by appropriate controls. The important features of this invention are that the underwater system is under a pressurized shield gas which protects all of the equipment as well as the electrical connections from the water. Other equivalents are possible. For example, box may be entirely jacketed with a cover in conduit relationship with the outer shielding gas bearing tubes. Rather than passing this gas through box 20, it is passed around and over it. In any event, the are itself is completely shielded by a double shield of protective gas such that arc welding under water may take place as if on dry land.

In a preferred embodiment of this invention a housing chamber adapted to provide a pocket of shield gas about the weld area and to house the tip of the welding gun itself is constructed to be generally of a hollow cylindrical shape with either end of the housing 120 defining an opening having a particular function. This housing 120 is shown in the various representations depicted in FIGS. 6-11, inclusive. The lower end of the housing (in the drawing), as is perhaps seen most clearly in FIGS. 6 and 10, has a transparent viewing plate 122. The viewing plate 122 is disposed in the lower portion of the housing 120 at an angle with respect to the axis of the cylindrical housing 120 to permit any water, welding particles, etc. to fall to the bottom, i.e., the lowermost extremity of the housing away from the central portion of the viewing plate. At this extremity, a boss 124 is formed and a bore or vent tube orifice 126 is provided therein. The orifice 126 is threaded at the interior portion as at 128 to accommodate a male threaded end 130 of a vent tube 132. The vent tube is L-shaped and has an open end and typically may be in the order of one-quarter to one-half inch in internal diameter to permit the escape of air pressure, water, welding particles, etc. as will be described hereinafter. Y

The viewing plate 122 is seated against a shoulder 134 formed in the interior walls of the housing 120 and is retained in place by a retaining gasket 136 which may be secured to the walls of the housing as by a plurality of screws 138.

The upper end of the housing chamber 120, as is seen in the drawings, particularly FIGS. 10 and 11, is seen to have an internal shoulder portion 140 adapted to accommodate a gasket sleeve which sleeve 142 may be removably inserted and fitted in the housing chamber 120 to be supported by the shoulder 140. A flexible gasket 144 is attached to the end face portion of the sleeve 142 to permit its contact with the welding workpiece 70 thereby to surround the immediate weld area 84. This gasket 144 may be formed of any suitable, flexible material, preferably, a porous rubber such as foam rubber or plastic. With a porous material, when the chamber 120 is pressurized, the shield gas may bubble through the gasket material and thereby prevent water from entering. Such bubbling action also facilitates and serves to lubricate the movement of the gasket material across the work-piece as the welding is accomplished. However, any flexible material capable of providing a good sealing contact with the work-piece 70 may be used.

Radial openings and 152 are also formed (typically in opposite walls) of the cylinder housing chamber 120. The orifice or opening 150 formed in the righthand wall (as seen in FIG. 10) is adapted to permit the entry of the welding gun itself. To facilitate this, a flexible sealing jacket 154 is placed over the opening and held in position by a retaining member 156 which may be secured as by screws or other suitable means to the walls of the housing 120. For this purpose, it is preferred that the opening 150 be in the form of a short length cylindrical member which may be molded contiguous with the housing 120 and radially disposed to the housing chamber 120, as perhaps seen most clearly in FIGS. 6 and 7. The particular configuration, however, is purely a function of design, The prime requisite be that it exceed in diameter the diameter of the welding gun tip portion that is to be inserted into the housing 120 and that the jacket 124 be flexible (rubber or suitable pliable plastic material may be used) and that it have a central opening therein of sufficient diameter to accommodate the gun itself and yet tightly engage the gun in a sealing relationship. To improve this seal the opening 157 in the jacket 154 may have an annular shoulder portion 158.

The welding gun itself may be of a conventional variety, such as that described hereinbefore, modified slightly as will be described. Thus, the gun 64 includes therein the conventional guide tube 62 which holds the consumable electrode 94 and through which shield gas from the pressurized box 20 (FIG. 4) is passed. The gun 64 is modified slightly over that described hereinbefore inasmuch as it has two switches, one switch 66 for controlling the welding current and a second switch 100 for controlling a solenoid actuated valve which in turn controls gas flow through a clearing jet 112. The clearing jet 112, as will be described hereinafter, is positioned adjacent the gun tip and is directed to permit a short blast of shield gas to clear debris and water from the weld area. The entire gun 64 is enclosed in a sleeve or conduit 74, as described hereinbefore, which houses the various shield gas lines as well as wires or cable which carry the welding current, lighting current and switch current. These wires and conduits may be in a composite cable as is the case in ordinary welding usage or may be run individually since they are all within the outer retaining sleeve 74.

The tip of the gun 64 has an annular support member 102 which annularly encloses the guide tube 62 and consumable electrode 94. The other modification of the gun necessary is that the exterior of the support member 102 be threaded to accommodate a cap nut 106 which holds an O-ring 108 against the end portion of the support 102 to provide a seal of the annular space between the guide member 62 and the annular support member 102 which normally contains an annular insulator. The cap nut 106 has an axial opening therein which is larger than the guide member 62 to further secure, insulate, and seal it from the guide member although insulating sleeves (not shown) suitably insulate and position the guide member 62 within the annular support 102. Finally, a sealing ring 116 terminates and seals the sleeve or conduit 74 to prevent the shielding gas pressure from escaping from the shielded gun 64.

Lastly, a small radial orifice 160 may be formed in the guide tube 62 to insure that sufficient shielding gas may pass through and around the consumable electrode 94 and out the tip or end portion of the guide tube 62. The shield gas lines for the clearing jet 112 as well as those supplying gas to insulate the gun assembly itself all may be derived from the gas supply tube 26 (FIG. 4). In like manner, the power for the switches 66 and 100 may be derived from the electrical line 28 (FIG. 4) to control the necessary solenoid actuated switches for controlling the welding current and the various gas supplies as required.

Shielding gas is supplied to the interior of the housing 120 through a suitable tubing (shown in phantom) 162 which in turn may be connected back to the shield gas supply tube 26 (FIG. 4) or, for that matter, directly back to the gas supply above the surface, as desired. The shield gas supply tube 162 is terminated in a conventional fitting 164 which is connected to an orifice 166 formed in what is illustrated as a hollow cylindrical light housing cavity 168 attached or formed contiguous with the light housing 168 at the orifice 152.,Shield gas from the tube 162 is allowed to pass into an annular passageway 170 formed by the housing 168 and a ringlike, radial diffuser 172. This radial diffuser has peripherally disposed, openings 174 therein so that the gas may diffuse slowly into the housing chamber from all points of the circumference of the diffuser and provide a smooth flowing path as denoted by the arrows 176 (FIG. 9). This prevents disturbing any water or other particles within the housing chamber and causing them to swirl and blur the welders vision.

To aid in positioning the diffuser 172, a transparent light window 180 is positioned within the light housing 168. To complete this assembly, a light 182 (illustrated only symbolically) is attached to the rear portion of the light housing so as to direct its light through the window 180 and the opening 152 into the interior of the housing 120. Although illustrated as being positioned perpendicularly to the axis of the housing,it is to be noted that this light may be directed directly toward the work-piece or away therefrom as may be desired and convenient in the design of the chamber. The light, itself, is held in position by a lamp holder 184 and is attached to the light housing 168 as by screws 186 or other suitable means. A sealing gasket 188 may be used to insure a water-tight seal as may be desired. Power for the light may be derived from the electrical power source leads 28 (FIG. 4). Suitable switch means for the light may be provided as necessary.

To use the unique underwater welding gun housing illustrated in FIGS. 6 through 1 1, inclusive, the welding gun 64 is inserted through the opening 156 in the jacket 154. The light 182 is turned on and the housing 120 positioned over the joint in the work-piece to be welded. Next the shield gas suppliesare turned on (usually the shield gas supply through the gun itself is maintained on to insure against the entry of water) to evacuate the water, etc. from the housing 120. Such evacuation is readily accomplished through the vent tube 132. Next the switch 100 is depressed which actuates the solenoid to pass a burst of clearing shield gas through the jet 112 directly into the weld area. This removes any residual water that might be present as well as any other dirt, particles, etc. Finally, the welding gun is positioned and as the work area is viewed through the viewing plate by the diver, the welding switch depressed, the weld is accomplished and the diver again surfaces to go to another job.

During the welding operation, as the weld is being accomplished along the bottom surface of an object, the vent tube 132 which is rotatable, is maintained in an upright position. During the time that a weld is being accomplished on a vertical surface, the vent tube 132 is maintained in a position slightly downward from the horizontal position. Similarly, when the weld is being accomplished upon a top surface, the vent tube is maintained in a downward position with respect to the surface. The adjustment of this vent tube does control to a degree the amountof shield gas that is discharged through the vent tube and may be adjusted as necessary by the welder.

It may be noted as seen most clearly in FIG. 11, that when welding a bottom surface, residual water as well as welding particles tend to fall onto the viewing plate. These, because of the sloping surface of the viewing plate, fall to the bottom most extremity of the housing where they are passed due to the flowing shield gas out through the vent tube 132. For this purpose the viewing plate may be positioned or constructed at any angle between 0 and relative to the axis of the housing 120. However, angles varying between 25 and 60 with respect to the axis are preferred. Extremely acute angles tend to obstruct the vision due to refraction and increase the required length of the housing. Conversely, angles approaching. 90 do not permit the welding particles to fall off the viewing plate. The welding particles would tend to accumulate and block the vision of the welder. Appropriate sloping of the plate prevents such accumulation.

A small problem is encountered when welding underwater surfaces from the top. Specifically, the escaping shield gas bubbles tend to obstruct the welders view. This may be prevented by the simple expedient of placing a funnel over the viewing plate such that these bubbles are deflected outwardly and away from the face of the welder.

The flexible gasket 1-44 and its mounting sleeve 142 which is insertable by a friction fit into the end of the housing chamber 120, may have different configurations to accommodate different surfaces. Thus to accommodate a cylindrical work-piece such as a pipe 200 illustrated in FIG. 12, the flexible gasket 202 (and the sleeve 204, if necessary) may have a curvature in their plane to conform to the exterior of the pipe 200. Other configurations might include interior and exterior corners, etc.

The invention described, using shield gases, as well as the housing, which is a preferred apparatus of the invention, permits high quality electrical welds to be accomplished. underwater using either AC or DC welding current and consumable electrodes with the same quality and with almost the same facility as may be accomplished in dry land welding.

While the invention has been disclosed herein in connection with certain embodiments and certain structural and procedural details, it is clear that changes, modifications, or equivalents can be used by those skilled in the art; accordingly, such changes within the principles of the invention are intended to be included within the scope of the claims below.

I claim:

1. A method of underwater electric arc welding a work-piece in which an underwater electric arc is drawn between an electrode of a welding gun and said work-piece to effect welding on said work-piece and in which water is kept from contact with said are and the weld area of said work-piece immediately adjacent said are by:

movably introducing at least a portion of said welding gun into a local housing having an aperture therein,

positioning said housing aperture against at least a portion of the weld area of said work-piece,

purging said local housing of water using a shielding gas under a pressure greater than the pressure of said water, and

welding said work-piece through said housing aperture in a region substantially free of water.

2. A method according to claim 1 which includes the additional step of positioning a pliable gasket between said aperture and the work-piece thereby to enhance the seal between said work-piece and said housing, and effecting relative movement between said housing and said work-piece during said welding.

3. A method according to claim 1 wherein said shielding gas forms an annular shield about said electrode, and which includes the additional step of introducing an additional shielding gas into said housing.

4. A method according to claim 1 which includes the additional step of moving said portable housing and said welding gun along said work-piece during welding in order to complete said weld.

S. A method according to claim 1 which includes the additional step of directing a burst of shielding gas through a jet at the weld area of the workpiece, thereby to aid in clearing the weld area.

6. A method according to claim 1 which includes the additional step of adjusting the point of discharge of a vent tube communicating with the interior of said local housing relative to said housing, thereby to adjust the pressure of said shield gas in said local housing.

7. A method according to claim 1 which includes the additional step of effecting relative movement during welding between each of said housing, said gun, and said work-piece, thereby to weld said work-piece.

8. A method according to claim 7 wherein the shielding gas is divided into small bubbles to lubricate the movement of said housing across said work-piece.

9. A method according to claim 7 which includes observing said welding on said work-piece through said housing during said welding, thereby to facilitate proper technique.

10. A method according to claim 7 which includes the additional step of adjusting the point of discharge of a vent tube communicating with the interior of said local housing relative to said housing, thereby to adjust the pressure of said shield gas in said local housing. 

1. A method of underwater electric arc welding a work-piece in which an underwater electric arc is drawn between an electrode of a welding gun and said work-piece to effect welding on said workpiece and in which water is kept from contact with said arc and the weld area of said work-piece immediately adjacent said arc by: movably introducing at least a portion of said welding gun into a local housing having an aperture therein, positioning said housing aperture against at least a portion of the weld area of said work-piece, purging said local housing of water using a shielding gas under a pressure greater than the pressure of said water, and welding said work-piece through said housing aperture in a region substantially free of water.
 2. A method according to claim 1 which includes the additional step of positioning a pliable gasket between said aperture and the work-piece thereby to enhance the seal between said work-piece and said housing, and effecting relative movement between said housing and said work-piece during said welding.
 3. A method according to claim 1 wherein said shielding gas forms an annular shield about said electrode, and which includes the additional step of introducing an additional shielding gas into said housing.
 4. A method according to claim 1 which includes the additional step of moving said portable housing and said welding gun along said work-piece during welding in order to complete said weld.
 5. A method according to claim 1 which includes the additional step of directing a burst of shielding gas through A jet at the weld area of the work-piece, thereby to aid in clearing the weld area.
 6. A method according to claim 1 which includes the additional step of adjusting the point of discharge of a vent tube communicating with the interior of said local housing relative to said housing, thereby to adjust the pressure of said shield gas in said local housing.
 7. A method according to claim 1 which includes the additional step of effecting relative movement during welding between each of said housing, said gun, and said work-piece, thereby to weld said work-piece.
 8. A method according to claim 7 wherein the shielding gas is divided into small bubbles to lubricate the movement of said housing across said work-piece.
 9. A method according to claim 7 which includes observing said welding on said work-piece through said housing during said welding, thereby to facilitate proper technique.
 10. A method according to claim 7 which includes the additional step of adjusting the point of discharge of a vent tube communicating with the interior of said local housing relative to said housing, thereby to adjust the pressure of said shield gas in said local housing. 